Julius c



y 1932- J. c. HOCHMAN ET AL 1,857,454

COMPUTING MACHINE I Original Filed Oct. 26, 1921 3 INVENTOR 7 60 zlcfliockmazzl 4y. 6 BY Gflfiegensr 4 MWW .AT ORNEY.

Patented May 10, 1932 nnirsn stares rarsnr JULIUS C. HOCHMAN AND GUS-TAVE O. DEGE'NER, OF NEVI YORK, Iii. '55., ASSIGNORS OF THREE-FOURTHS T9 SAID HGCHMAN ANS) ONE-FOURTH T9 MAURICE SAMBURG COMPUTING IVIAGHINE Application filed October 26, 1921, Serial No. 510,545. Renewed June 7, 1928.

Our present invention relates to computing machines, and particularly to safeguarding elements to assure a registration in every case corresponding accurately to the operation performed upon the machine.

Among-the objects of the invention are to provide simple, effective, easily operable and reliable means to prevent reversal of the operation of the mechanism or of any part thereof, except at the end of the stroke, and to pre vent advance of operating parts by inertia.

The invention although broadly applicable to computing machines of various types has a preferred application to machines of the type in which the totalizer is operated directly by the actuation of each of the number keys.

With regard more specifically to computing machines of the type referred to, it is a feature of our invent-ion to provide a single, simple full stroke mechanism normally disconnected from all of the keys and to provide automatic means set into action by the operation of any of the keys to bring the actuated key into co-action with said full stroke mechanisn the latter then operating to prevent reversal before the end of the stroke.

According to another feature of our invention, the full stroke mechanism is of doubleacting character, that is, it performs, in additi n to the function just stated, the function preventing a second depression of the key before complete return thereof to home position.

Another object is to provide a full stroke mechai 'sm which while effecting its reversal preventing function throughout the operative and throughout the return strokes, will nevertheless permit of excess operation at the ends of the strokes to make up for wear of the parts.

lane ier feature is the use of the full stroke mocha; ism the control for other safeguarding mechanisms which it is desired to time accurately, preferably for control of the overthrow prevention pawl for the master wh eel.

According to another feature, guard means is provided to prevent shift of the overthrow gn'evention p awl into coacti on with the master wheel except at the end of the operative key stroke or to prevent movement of the pawl out of operative position except at the end of the return key stroke and in the preferred embodiment, both said means are combined.

In the accompanying drawings in which is shown one of various possible embodiments of the several features of the invention,

Fig. 1 is a fragmentary elevation of the machine, illustrating a preferred embodiment of the invention,

Fig. 2 is a fragmentary detail on a larger scale, illustrating the action of the full stroke connection plate,

Fig. 3 and Fig. 4 are fragmentary details on an enlarged scale showing the operation of the full stroke mechanism, the triangular bar 60 being omitted for the sake of clearness,

Fig. 5 is a view similar to Fig. 3 of a modification,

Fig. 6 is a perspective view of one of the timing guards, and;

Fig. 7 is a sectional view taken along the line 7-7 of Fig. 3, triangular bar 60 being here shown in its correct position.

Similar reference characters refer to similar parts throughout the several views of the drawings.

It may be noted at the outset that certain of the features of the invention are broadly applicable to computing machines of various types. The drawings show an embodiment of the invention especially applicable to a special preferred type of machine. This machine includes a succession of numbered keys 1 connected through mechanism (not shown in detail) for actuating the master wheel 2 mounted upon a totalizer actuating shaft 3.

In this machine, a control plate 4 is overlapped at its upper edge by tongues 5 at the upper ends of the key member bars 6, that are slidable in grooves 7 in the base plate B, so that upon depression of any key, the corre sponding tongue 5 will actuate the control plate to shift or translate the same therewith for performing a variety of functions, some of which will be set forth in detail below. The machine also includes a control shaft 8 rotatable through the same angle regardless of the number value of the actuated key for performing a variety of functions, one

of which will be set forth below and the remainder of which are not material to the invention. In the preferred embodiment, spring means (not shown) is included to effect the return of the parts to home position after each key depression. For further de tails as to the machine in which the preferred embodiment of the present invention is shown, reference may. be had to the Patents Nos. 1,609,205 and 1,609,206 granted to lilaurice Samburg and Julius C. Hochman on November 30, 1926, it which the machine constitutes an attachment upon an ordinary typewriter, the numberkeys of wl ch. are in the path of operation of the computing machine keys.

Since the control plate in machines of the general type referred to, is to perform or initiate certain automatic operations at the era treme ends of its stroke, it is important that it shall accurately complete its operative stroke without possibility of return from between the ends of the stroke and that it shall similarly complete its return stroke without possibility of a second operation from between the ends of said return stroke. For this purpose, a full stroke mechanism shown on an enlarged scale in Figs. 3 and is provided. The full stroke mechanism includes a bar 9 slidable in a groove 10 similar to the grooves 7 for the key bars, said bar having tongues 11 and 12 straddling the lower and upper edges respectively of the control plate 4, so as to slide as a unit therewith. Rigid with the full stroke bar is a rack 13 projecting from the bar and providing end should 14 and 15 for purposes which will be set forth below, said rack having preferably symmetrical teeth 16 at one ed ge thereof. For coaction with the racks we provide a pair of identical pawls 17 and 18,. symmetrically arranged shown. Pawl 18 is pivoted as at 19 to the base plate B and is urged in counter-clock wise. direction by a coiled spring 2Q, 03 a. 'l of which presses against a stud in the b e plate and the other end of which fits into a groove 22 in the pawl. Pawl 17 is symmetrically arranged with respect to pawl 18, a coiled spring 23 urging pawl 17 in a clockwise direction, and pressing at one end against a stud 24. symmetrically interposed between the pawls is a central or transfer pawl 25 of symmetrical construction loosely mounted about a pivot stud an preferably a squared teeth 27 nroi the path of movement 01 V aclt pawl 25 has integral upstanding lu 29 at its opposite sides, lug 28 being in the path of a tail on pawl 17 and lua; 29 in the path of a similar tail 31 on 1 tails 30 and 31 extend adjacent pin 26, the latter serving as a stop for limiting the mo ment of the pawls in the direction of the respective coil spring impulses.

Fig. 3 shows the device in home position or at the uppermost end of its stroke. The parts are so constructed and arranged that when at the lowermost end of the stroke, or when the control plate is at the end of the operative stroke, the rack 13 will occupy the position indicated in dotted lines in Fig. 3, symmetrical. with respect to the position shown in full lines.

In operation, as a number key is depressed, the tongue 5 thereon actuates the control plate 4 and the latter moves the full stroke bar 9 downwardly therewith. In this downward movement, the rack 13 will ratchet over the tooth 32 of pawl 18 and against the re sistance of the spring 20. Vhile the rack is in engagement with tooth 32, it will be apparent that a return movement of the rack cannot take place without counterclockwise pawl movement, which in turn is blocked by the rack. As the stroke proceeds the end 14 of the rack contacts with the tooth 27 on pawl 25 and shifts the latter about its pivot pin 26, bringing the lug 28 into engagement with tail 30 on pawl 17 and thereby shifting the latter about its pivot to clear the rack 13 as will be apparent from Fig. 4. It willbe apparent that if the tooth of pawl 17 were permitted to engage the rack in the downward portion of the stroke, it would lock the rack against continued downward movement. In the continued downward movement, the rack 13 will ratchet over the point 33 of the squared tooth 27 on the transfer pawl 25. After the upper end 15 of the rack clears pawl 18, the transfer pawl 25 alone performs the function of preventing return of the full stroke bar. As the downward stroke proceeds, a little beyond the position shown in Fig. 4, the transfer pawl 25 clears the rack and immediately thereafter the spring 23 expands to snap the pawl 17 about its pivot in a clockwise direction against the upper tooth 52 of the rack, and tail 30 of the pawl by its coaction. with lug 28 concurrently shifts the transfer pawl 25 to the symmetrical position shown in Fig. 3. The operative stroke should ordinarily be completed now. However, as all three pawl teeth are above the rack, continued displacement in. the operative direction is permitted to con'ipensate for any eventual loose- :iess resulting from wear, small or substantial in any or all parts of the calculating train. The parts are now in the position shown in dotted lines in Fig. 3.

Briefly summarizing, the operative stroke proceeds as follows The rack 13 first ratchet-s over the pawl tooth 32 then comes into coaction with transfer pawl tooth point 33, then clears pawl tooth 32, so that the transfer pawl tooth prevents return movement during the remainder of the stroke. The transfer pawl member, moreover, shifts the pawl 17 laterally to clear the rack at the latter part of the operative stroke, and pawl 17 is released to coact with the rack only after the lit 1 transfer pawl has cleared the latter, the pawl 17 at such time, however, permitting continued movement of the rack without limitto-compensate for wear. Exactly the same operation will proceed in the reverse direction on the return stroke, as is immediately apparent from the absolute symmetry of the parts. It would accordingly be superfluous to repeat the detailed description with regard to the return stroke action.

It will thus be seen that we have provided a simple full stroke mechanism which can be depended upon to prevent reversal of the stroke in either direction except at the end of the operative stroke and at the end of the return stroke. The full stroke mechanism, in other words, is doubleacting, preventing return movement from any point between the endsof the operating stroke, and preventing a repeated stroke in the operative direction from any point between the ends of the return stroke. Furthermore, it will be seen that the parts are, nevertheless, so constructed that additional displacement is permitted at the end of both the operating and return strokes to compensate for wear of the parts.

Only one of the pawls 17 and 18 will at any time coact with the rack, the transfer pawl pushing aside the lower main pawl on the down stroke as the rack comes into the ran ge thereof and pushing aside the upper main pawl on the upper stroke as the rack in its return movement comes into the range thereof, so that while the rack can bridge both of the pawls 17 and 18, amming of the construction cannot occur, since both of the pawls cannot concurrently engage the rack teethv Means is preferably provided to automatically effect a connection of the single full stroke mechanism with any number key as the same is operated, to place the key under the restraining influence of said mechanism.

In the preferred embodiment, a locking connection is automatically effected between the operated number key bar and the con trol plate, so that the full stroke mechanism being connected directly to the control plate, will also restrain the operated key. In the preferred embodiment shown, a full stroke connection plate 84 is mounted in back of the control plate 4, that is, between the control plate and the base plate B and. is c nected to move within the former. For purpose, preferably, studs 35, 36 and 37, mounting a. roller 38, extend outwardly from the full stroke connection plate 34, through elongated slots 39 in the control plate. full stroke connection plate has a series of locking teeth 40 each with a horizontal lower side 41, one corresponding to each key bar, said teeth being normally disposed preferably toward the left of triangular .th 42, each with a horizontal upper side 43, one formed integral with each of the key bars and near the tongues 5 thereof. As best seen in Fig. 2, the locking teeth on the full stroke connection plate are placed so as to enter by lateral movement between the triangular teeth 42 and the tongues 5. Connected to the frame of the machine, there is preferably a stationary cam piece 44 having a shank 45 and a hook-shaped upper end 46 straddling the central roller 88. The shank has an oblique edge 47 and the hook an oblique edge 48 forming a track for the roller. A screw 49 secures the upper end of the cam in place, and serves as a stop element for the control plate when the latter is at the upper extremity of its stroke. The upper edge of the control plate is preferably formed with a notch underneath the cam, and not shown, to provide operating clearance around the screw 49. The cam piece is preferably near the center of the control and full stroke connect-ion plates, and also serves to prevent buckling thereof.

Upon depression of any key, the control plate is urged downwardly by the tongue 5 and carries with it the full stroke connection plate. At the commencement of the stroke, oblique cam surface 47 urges roller 38 and with it the entire full stroke connection plate toward the right causing the corresponding tooth edge 41 to pass over and into engagement with the corresponding tri- L angular tooth 42 of the depressed key. The

full stroke connection plate, thus has an oblique or combined downward and lateral movement, and the angle of the teeth 40 and 41 preferably corresponds to this obliquity, so that the teeth 40 corresponding to the key other than that depressed will readily pass under the associated teeth 42. All key members other than that actuated thus remain free of the connection plate. As the downward movement proceeds, the roller 38 travels along the vertical edge 50 of the cam piece shank, which thus holds the connection plate against unlocking movement with respect to the actuated key. The key bar being guided in its groove 7 and the connection plate being firi'nly held toward the ri 'ht by the vertical edge 50 of the cam piece shank, the teeth 40 and 42 cannot become prematurely disengaged by relative lateral motion. The key bar is held against upward movement relative to the connection plate 34 by the engagement of tooth edge 43 with tooth edge 41 and against downward movement by the tongue and the control plate 4. The control plate is accurately guided against displacement toward or from the base plate, so that the interposed full stroke connection plate cannot move in a direction away from the base plate. The enacting teeth 40 and 42 therefore, cannot become prematurely disengaged by relative movement toward or from base plate. Thus, the key bar is firmly and effectively locked to the full stroke connection plate. As the key-stroke pro- I. the

ceeds, the control plate moves substantially as a rigid unit therewith, throughout the operative and return stroke, and the full stroke mechanism operates as heretofore described. As the key on its return stroke approa'ches home position, the roller 38 comes into engagement with the inclined cam sur face 48 on hook 46 and is, therefore, at the extreme upper edge of the stroke shifted toward the left to disengage the tooth 40 from the triangular tooth 42 on the actuated key, thereby restoring the parts to normal position in which the connection plate is disconnected from all of the key members. Thus, the control plate cannot move in advance of the operated key during the operative stroke, neither can the key member move by inertia or otherwise in advance of the control plate in the return stroke. The operated key is locked to the control plate at the commencement of the operative stroke and not unlocked until the end of the retvrn .pawls.

Since the full stroke mechanism provides an effective lock against reversal of movement except at the very extremities of the operative and return strokes, it can be effectively used particularly as the governing means for other safeguarding mechanisms and control means in the computing mechanism. In the preferred embodiment, the full stroke mechanism is shown applied for controlling the pawl which prevents overthrow of the master wheel 2. It may be noted that it is desirable in computing machine constructions generally to leave the master wheel entirely free throughout the operative stroke for transferring the number to the totalizer without substantial resistance and to effectively lock the master wheel against any possibility of inertia overthrow at the very extremity of the operative stroke and to keep the master wheel in locked position, throughout the return stroke. Our control plate in view of the accuracy of its action, as heretofore pointed out, can be used effectively to accurately initiate the locking action substantially exactly at the extremity of the locking stroke. In the preferred embodiment, the master wheel locking pawl 60 is pivoted to the triangular bar 60 of the construction about a pin 61 and has a triangular tooth 62 for ready entry between the preferably bevcled teeth 63 of the masterwheel and has a tail 64 overlapping the full stroke bar and between the end 15 of the rack and the shoulder 11 that engages the control plate. It will immediately be apparent that as the end of a key stroke is reached, shoulder 11 will engage the upper part of the tail 64, and will shift the pawl 60 about its axis 61 to cause the triangular tooth 62 to enter between the beveled teeth 63 of the master wheel. The parts are so proportioned that the entry of the locking pawl is completed substantially exactly at the extremity of the operating stroke. Upon the return stroke, the edge 15 of the rack comes into engagement with the lower edge of the tail 64 and shifts the pawl 60 out of coaction with the master wheel, leaving the latter free to rotate in response to the subsequent actuation of a number key. The end 15 of the rack is so positioned that the disengagement of the pawl takes place accurately when the parts have reached home osition.

Means is prefera ly provided to prevent undesired shifting of the master wheel locking pawl 60 into or out of active position. Specifically, after the pawl has been shifted to locked position, the means prevents the possibility of disengagement except at the extremity of the return stroke and preferably also after the pawl has been disconnected from the master wheel, the means prevents the possibility of re-engagement except at the end of the operating stroke. This result is achieved in the preferred embodiment by providing upon the control shaft 8 a timing guard 65 consisting of a hub 66 pinned or otherwise secured to the shaft, and provided with a continuous flange 67 and with a second flange 68 having preferably gaps 69 and 70 for a purpose appearing below. The pawl has preferably a pairof projections or pins 71 and 72, pin 72 being located beyond the continuous flange 67 and pin 71 being adapted to enter between the two flanges as shown in Fig. 1 and when the timing guard is in appropriate position free to pass beyond the flange 68 of the guard, through one of the gaps. The gaps in the timing guard are so positioned that in the course of the operating stroke, as the control shaft 8 is rotated, a continuous segment of flange 68 blocks the passage of pin 71 and thus locks the pawl against entering into coaction with the master wheel, while at the extremity of the operating stroke, gap 69 comes into alignment with pin 71 so that the shoulder 11, which at that time comes into coaction with the tail 64 of the pawl, will freely shift said pawl into coaction with the master wheel, the pin 71 emerging through the gap 69 and passing beyond the flange 68. The pin 72 by its coaction with the continuous flange 67 acts as a stop to limit the entering movement of the pawl and prevents jamming. When the return stroke commences, the control shaft 8 rotates in reverse direction and the gap 69 will pass out of alignment with pin 71, so

that a continuous portion of the flange 68 will block the return of pin 71 and will thus prevent the pawl from coming out of engagement with the master wheel at any part of the return stroke. When the return stroke is completed, however, the control shaft has been rotated to such extent as to bring the gap 7 0 into alignment with the pin 71 and at that time theedge 15 of the rack will contact with the tail64 and shift the pawl out of engagement with the master wheel, the pin 71 entering freely through gap 70 between the two flanges 68 and 67 in the timing guard and the continuous flange 67 by its coaction with pin 71 limits the movement of the pawl in a direc tion away from the master wheel.

- Preferably a dished spring 95 is interposed between the head of pin 61 and the pawl 60. This spring'exerts sufficient friction to prevent bounce-back of the pawl before the gap 69 or 70 has moved out of registry with pin 71.

In Fig. 5 is shown an alternative form of full stroke locking mechanism in which a single coil spring 80 serves to urge the two symmetrically arranged pawls 81 and 82 in clockwise and counterclockwise direction re spectively toward operative engagement with the rack, the ends of said coil spring being connected as at 83 over hooks 84; formed integral with the pawls. In this embodiment, the stud for the transfer pawl 85 does not coact with the pawls for performing the blocking function, as it does in the other embodiment but is clear of the pawls at all times, the blocking function being performed by studs 86 and 87 which coact with lugs 88 and 89 respectively on the pawls 81 and 82. In this embodiment, also, it is noted that the lugs 90 and 91 on the transfer pawl which act to shift respectively the pawls 81 and 82 out of therange of the rack have their widths extending parallel to the rack when the device is in the neutral position shown, rather than perpendicular to the rack, as in the other embodiment. A ledge or shoulder 98 on the base plate in the path of the key members acts as a stop therefor, thus taking the strain from the tooth of pawl 81, if pressure is applied at the limit of the stroke. If desired, a similar .shoulder may be provided for limiting the return stroke, but as the pressure of the finger is at no time exerted on the tooth of pawl 82, the latter shoulder is preferably dispensed with.

It will, of course, be understood that although we prefer to employ a double-acting full stroke mechanism, that is, one for preventing return movement of an operating part before the'end of the operative stroke is reached, as well as for preventing a repeated operative stroke during the return movement, many of the features of the mechanism could be applied in a full stroke mechanism for performing only one of the two functions. It will also be apparent that, if

desired, a separate and distinct full stroke mechanism of the type shown could be applied to each of the number keys.

T he full stroke connection plate in the prefer ed embodiment serves to connect a single anism with any one of a set n he s, to move in unison with the opera ed kc or the operative as well as for the return stroke. It will, of course, be ap parent that this fuil stroke connection piece may designed to restrain the actuated key t n'iovement relative thereto in only one d ection instead of in both directions.

"estiy. the full stroke mechanism can be used in combination with a connection element of construction differing widely from the preferred form disclosed for automatically establishing connection with an operating key or other member and the specific form of full stroke connection plate may be used in combination with a full stroke mechanism of any of a wide variety of constructions, although the specific combination shown and described is preferred.

It will also be seen that although we have shown a pawl for preventing overthrow of the master wheel, actuated by parts of the full stroke mechanism, one or more safeguarding DIQChZlHiSlflS may be so actuated instead of, or in addition to, the master wheel locking pawl; also that the timing guard associated. with the master wheel locking pawl aithough of special utility in the combination shown is of general utility in numerous other reiations.

it will be understood that the plate 34 is not limited in its application to use in connection with full stroke mechanisms, but may be applied as an interlock automatically ctuated for any of a wide variety of purposes upon operation of any number key.

We claim 1. In a full stroke mechanism, in combina tion, a member including a toothed portion having symmetrical teeth, a pair of identical pawls symmetrically arranged with respect to said member, one end of said toothed portion moving beyond one of the pawls in its travel toward the other and the other end moving beyond the other pawl in its travel toward the first pawl, a member interposed between said pawls and actuated by said toothed portion to deflect one pawl out of contact with the toothed portion as the latter reaches the pawl in the operative stroke, and to similarly deflect the other pawl as the toothed portion reaches said other pawl in the return stroke, said interposed member including a tooth for performing the locking function of the second pawl after the toothed portion has cleared said pawl and before the end of the stroke, and to perform the function of the first pawl after the toothed portion in its return movement has cleared said first pawl.

2. In a full stroke mechanism, in combination, a slidable rack, 21 pair of pawl members in the path of action of said rack, spring means to urge said pawls one in a clockwise and the other in a counterclockwise direction, a central pawl member symmetrically disposed with respect to said two pawls and having a symmetrical tooth extending in the path ofsaid rack, said first pawls having projections in the path of movement of said central pawl, whereby when the latter is de flected by the rack in one or the other direc tion, one or the other pawl will be shifted to clear the rack, and stop means adapted to coact with said first pawls to effect a locking action of the pawls against reversal of stroke.

3. In a computing machine, in combination, a master wheel, a pawl to prevent overthrow thereof, and a full stroke mechanism so associated with said pawl that an abutment integral with an element thereof will throw the pawl into locking position at the end of the operative stroke.

4. In a computing machine, in combination, a master wheel, a pawl to prevent overthrow thereof, a full stroke mechanism so associated with respect to said pawl that abutments integral with an element thereof will throw the same into locking position at the ii end of the operative stroke and will move said pawl out of operative position at the end of the return stroke.

5. In a computing machine, in combination, a master wheel, a pawl to prevent over throw thereof, and a full stroke mechanism so associated with respect to said pawl that an abutment integral with an element thereof, throws the same out of operative or locking position at the end of the return stroke.

6. In a computing machine, in combination, a master wheel, a full stroke element, a pawl having a tail in the path of abutments on said element, to urge the tooth of said pawl into coaction with said master wheel at the end of the operative stroke and to return said pawl to inoperative position at the end of the return stroke. 7

7. In a computing machine, in combination, a master wheel, a slidable element having a full stroke rack thereon, pawl means for coaction therewith, an auxiliary shoulder on said element, a pawl for coaction with said master wheel to prevent overthrow, said )ElWl having a tail extending between said shoulder and said rack and in the path of both, said shoulder being so disposed that it contacts with said tail at the end of the operative stroke to move said pawl into coaction with said master wheel and the end of said 1 rack being in a position such as to engage said tail to disengage the pawl from the master wheel at the extremity of the return stroke.

8. In a computing machine, in combination, a master whe l, a pawl for coaction ii therewith to prevent overthrow, a control block movement of said pawl at a time when 5 the control member is between the extremltles of its range of movement, said timing guard having gaps coming into appropriate registry with the pawl at the ends of the stroke to permit shift of the pawl at such stroke ends.

9. In acomputing machine, in combination, a master wheel, a pawl for coaction therewlth to prevent overthrow, a control shaft rotatable through the same angle regardless of the number value of the actuated key, a timing guard rotatable with said shaft, a projection on said pawl extending to one side of said guard, said projection coming into registry with a gap in said guard at the end of the operative stroke to permit shift of the pawl into coaction with the master wheel and coming into registry with a gap in the guard near the end of the return stroke to permit return movement of said projection in order to disengage the pawl from the master wheel.

10. The combination set forth in claim 9 in which the guard has a flange and two projections are provided on the pawl at opposite sides of the flange, said flange limiting the range of displacement of said pawl toward or from the master wheel by contact of one or the other projection therewith,

11. In a computing machine including a totalizer having a master wheel, in combination, a pair of control elements, each operable through an identical range for each actuation of the master wheel, a pawl coacting with said master wheel to prevent overthrow, one of said control elements having associated therewith a timing guard to prevent shift of said pawl to operative position prior to the end of an operative stroke and to prevent shift of said pawl from operative position prior to the end of a return stroke, the other of said elements being connected to said pawl to positively shift the same to or from operative position when the timing guard is in the correct position permitting the shift.

12. In a computing machine including a totalizer having a master wheel, in combination, a translating control member and a rotating control member each operable through an identical range for each actuation of the master wheel, a pawl coacting with said master wheel to prevent overthrow, said translating control member coacting with said pawl to shift the same to or from operative position at appropriate times, and a timing guard carried by said rotating control member and in the path of said pawl to prevent shift thereof to operative position '7 prior to the end of an operative stroke and from operative position prior to the end of a return stroke.

Signed at New York city, in the county of 5 New York and State of New York this 7th day of Oct. 1921.

JULIUS C. HOCHMAN. G. O. DEGENER. 

